SARS-CoV-2 disease severity and transmission efficiency is increased for airborne compared to fomite exposure in Syrian hamsters

Julia R Port,Jonathan E Schulz,Irene Offei Owusu,Myndi Holbrook,Robert Fischer,Trenton Bushmaker,Craig Martens,Claude Kwe Yinda,Vincent J Munster,Victoria A Avanzato,Chad S Clancy,Neeltje Van Doremalen

doi:10.1038/s41467-021-25156-8

Julia R Port, Jonathan E Schulz + Show 10 more

Open Access

https://doi.org/10.1038/s41467-021-25156-8

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Abstract

Transmission of SARS-CoV-2 is driven by contact, fomite, and airborne transmission. The relative contribution of different transmission routes remains subject to debate. Here, we show Syrian hamsters are susceptible to SARS-CoV-2 infection through intranasal, aerosol and fomite exposure. Different routes of exposure present with distinct disease manifestations. Intranasal and aerosol inoculation causes severe respiratory pathology, higher virus loads and increased weight loss. In contrast, fomite exposure leads to milder disease manifestation characterized by an anti-inflammatory immune state and delayed shedding pattern. Whereas the overall magnitude of respiratory virus shedding is not linked to disease severity, the onset of shedding is. Early shedding is linked to an increase in disease severity. Airborne transmission is more efficient than fomite transmission and dependent on the direction of the airflow. Carefully characterized SARS-CoV-2 transmission models will be crucial to assess potential changes in transmission and pathogenic potential in the light of the ongoing SARS-CoV-2 evolution.

Highlights

Transmission of SARS-CoV-2 is driven by contact, fomite, and airborne transmission
Airborne transmission can be defined as humanto-human transmission through exposure to large droplets and small droplet nuclei that can be transmitted through the air; whereas airborne transmission includes transmission through both large and small droplets, true aerosol transmission occurs via droplet nuclei particles smaller than 5 μm
That aerosol inoculation causes severe respiratory pathology, higher virus loads and increased weight loss while fomite exposure leads to milder disease manifestation

Summary

Introduction

Transmission of SARS-CoV-2 is driven by contact, fomite, and airborne transmission. The relative contribution of different transmission routes remains subject to debate. Experimental research has shown viral RNA can consistently be detected for up to seven days on surfaces but, the infectious virus degrades rapidly, with limited presence after two days[12] This discrepancy between the consistent detection of SARS-CoV-2 viral RNA and the relatively short time frames when viable virus can be detected directly hampers our ability to translate SARS-CoV-2 RNA detection on hospital surfaces and in air samples to understanding transmission and relative contribution of fomites and airborne virus. That aerosol inoculation causes severe respiratory pathology, higher virus loads and increased weight loss while fomite exposure leads to milder disease manifestation. Using this data, we develop a hamster airborne and fomite transmission model to confirm our findings in a natural transmission setting. This suggests that airborne transmission may be of increased relevance in the spread of SARS-CoV-2 and highlights the relevance of targeted countermeasures

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